This invention relates to a seal which engages both the screw and nut in a ball screw assembly.
Known ball screw assemblies include an internally threaded nut positioned on an externally threaded screw. A plurality of balls received in a space defined between the inner and outer threads guide relative movement between the nut and screw. Ball screw assemblies are typically used to control precision movement, and it is important to ensure that they operate smoothly and properly. To this end, it is necessary to seal the space between the nut and screw to prevent lubricant from escaping, and to prevent the influx of foreign particles.
Due to the complex, relatively moving surfaces between the external thread on the screw and an inner peripheral surface of the nut, it has proven somewhat difficult to seal the space between the nut and screw. The prior art has used a seal with a seal thread disposed in the screw thread. There is clearance between the seal thread and the screw thread, and the seal is closely spaced from a inner peripheral surface of the nut. This type of prior art seal has not positively engaged and sealed a surface of either the nut or the screw.